Tuberculosis case finding for vaccine trials in young children in high-incidence settings: a randomised trial

Treatment Response in Pediatric Pulmonary Tuberculosis-A Prospective Longitudinal Study

BACKGROUND

Data are limited on the resolution of symptoms and signs in children treated for pulmonary tuberculosis (PTB) and whether this resolution differs from children with other lower respiratory tract infections (LRTIs).

METHODS

A prospective study of children ≤ 15 years presenting with features suggestive of PTB was performed. Clinical, microbiological, and radiological investigations were done at enrollment. Symptoms and clinical features were measured 1, 3, and 6 months after enrollment. Participants were categorized into 3 groups based on National Institutes of Health consensus definitions: confirmed PTB, unconfirmed PTB, and unlikely PTB (children with other LRTIs). Univariable and multivariable logistic regression modeling was used to investigate predictors of persistence of symptoms or signs.

RESULTS

Among 2019 participants, there were 427 (21%) confirmed, 810 (40%) unconfirmed, and 782 (39%) with unlikely PTB. Of 1693/2008 (84%) with cough and 1157/1997 (58%) with loss of appetite at baseline, persistence at 3 months was reported in 24/1222 (2%) and 23/886 (3%), respectively. Of 934/1884 (50%) with tachypnoea and 947/1999 (47%) with abnormal auscultatory findings at baseline, persistence at 3 months occurred in 410/723 (57%) and 216/778 (28%), respectively. HIV infection and abnormal baseline chest radiography were associated with persistence of symptoms or signs at month 3 (adjusted odds ration [aOR] 1.6; 95% confidence interval [CI]: [1.1, 2.3] and aOR 2.3; 95% CI: [1.5, 3.3], respectively]. The resolution of symptoms and signs was similar across categories.

CONCLUSIONS

Symptoms resolved rapidly in most children with PTB, but signs resolved more slowly. The pattern and resolution of symptoms or signs did not distinguish children with PTB from those with other LRTIs.

Comparative yield of different active TB case finding interventions in a large urban TB project in central Uganda: a descriptive study

INTRODUCTION

Systematic screening for TB among patients presenting to care and among high risk populations is recommended to improve TB case finding. We aimed to describe the comparative yield of three TB screening approaches implemented by a large urban TB project in central Uganda.

METHODS

We abstracted data on the screening cascade from 65 health facilities and their surrounding communities (numbers screened, with presumptive TB, receiving a diagnostic test and diagnosed with TB) from the different clinic and community TB registers.

RESULTS

From January 2018 to December 2019, 93,378 (24%) of all patients screened at health facilities had presumptive TB; 77,381 (82.9%) received a diagnostic test and 14,305 (18.5%) were diagnosed with TB. The screening yield (the number of patients diagnosed with TB out of all patients screened) was 0.3% and was three times higher among men than women (0.6% vs 0.2% p<0.01). During targeted community screening interventions, 9874 (21.1%) of all patients screened had presumptive TB; 7034 (71.2%) of these received a diagnostic test and 1699 (24.2%) were diagnosed with TB. The screening yield was higher among men, (3.7% vs 3.3% p<0.01) and highest among children 0-14 (4.8% vs 3.2% p<0.01).

CONCLUSION

Targeted community TB screening interventions improve access to TB diagnosis for men and children 0-14 years.

Incidence of tuberculosis and the influence of surveillance strategy on tuberculosis case-finding and all-cause mortality: a cluster randomised trial in Indian neonates vaccinated with BCG

Introduction

Accurate tuberculosis (TB) incidence and optimal surveillance strategies are pertinent to TB vaccine trial design. Infants are a targeted population for new TB vaccines, but data from India, with the highest global burden of TB cases, is limited.

Methods

In a population-based prospective trial conducted between November 2006 and July 2008, BCG-vaccinated neonates in South India were enrolled and cluster-randomised to active or passive surveillance. We assessed the influence of surveillance strategy on TB incidence, case-finding rates and all-cause mortality. Predefined criteria were used to diagnose TB. All deaths were evaluated using a verbal autopsy.

Results

4382 children contributed to 8164 person-years (py) of follow-up (loss to follow-up 6.9%); 749 children were admitted for TB evaluation (active surveillance: 641; passive surveillance: 108). The TB incidence was 159.2/100 000 py and the overall case-finding rate was 3.19 per 100 py (95% CI 0.82 to 18.1). Whereas, the case-finding rate for definite TB was similar using active or passive case finding, the case-finding rate for probable TB was 1.92/100 py (95% CI 0.83 to 3.78) with active surveillance, significantly higher than 0.3/100 py (95% CI 0.01 to 1.39, p=0.02) with passive surveillance. Compared to passive surveillance, children with active surveillance had decreased risk of dying (OR 0.68, 95%CI 0.47 to 0.98) which was mostly attributable to reduction of death from pneumonia/respiratory infections (OR 0.34, 95%CI 0.14 to 0.80).

Conclusion

We provide reliable estimates of TB incidence in South Indian children <2 years of age. Active surveillance increased the case-finding rates for probable TB and was associated with reduced all-cause mortality.

Interventions to increase tuberculosis case detection at primary healthcare or community-level services

BACKGROUND

Pulmonary tuberculosis is usually diagnosed when symptomatic individuals seek care at healthcare facilities, and healthcare workers have a minimal role in promoting the health-seeking behaviour. However, some policy specialists believe the healthcare system could be more active in tuberculosis diagnosis to increase tuberculosis case detection.

OBJECTIVES

To evaluate the effectiveness of different strategies to increase tuberculosis case detection through improving access (geographical, financial, educational) to tuberculosis diagnosis at primary healthcare or community-level services.

SEARCH METHODS

We searched the following databases for relevant studies up to 19 December 2016: the Cochrane Infectious Disease Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL), published in the Cochrane Library, Issue 12, 2016; MEDLINE; Embase; Science Citation Index Expanded, Social Sciences Citation Index; BIOSIS Previews; and Scopus. We also searched the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP), ClinicalTrials.gov, and the metaRegister of Controlled Trials (mRCT) for ongoing trials.

SELECTION CRITERIA

Randomized and non-randomized controlled studies comparing any intervention that aims to improve access to a tuberculosis diagnosis, with no intervention or an alternative intervention.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed trials for eligibility and risk of bias, and extracted data. We compared interventions using risk ratios (RR) and 95% confidence intervals (CI). We assessed the certainty of the evidence using the GRADE approach.

MAIN RESULTS

We included nine cluster-randomized trials, one individual randomized trial, and seven non-randomized controlled studies. Nine studies were conducted in sub-Saharan Africa (Ethiopia, Nigeria, South Africa, Zambia, and Zimbabwe), six in Asia (Bangladesh, Cambodia, India, Nepal, and Pakistan), and two in South America (Brazil and Colombia); which are all high tuberculosis prevalence areas.Tuberculosis outreach screening, using house-to-house visits, sometimes combined with printed information about going to clinic, may increase tuberculosis case detection (RR 1.24, 95% CI 0.86 to 1.79; 4 trials, 6,458,591 participants in 297 clusters, low-certainty evidence); and probably increases case detection in areas with tuberculosis prevalence of 5% or more (RR 1.52, 95% CI 1.10 to 2.09; 3 trials, 155,918 participants, moderate-certainty evidence; prespecified stratified analysis). These interventions may lower the early default (prior to starting treatment) or default during treatment (RR 0.67, 95% CI 0.47 to 0.96; 3 trials, 849 participants, low-certainty evidence). However, this intervention may have may have little or no effect on treatment success (RR 1.07, 95% CI 1.00 to 1.15; 3 trials, 849 participants, low-certainty evidence), and we do not know if there is an effect on treatment failure or mortality. One study investigated long-term prevalence in the community, but with no clear effect due to imprecision and differences in care between the two groups (RR 1.14, 95% CI 0.65 to 2.00; 1 trial, 556,836 participants, very low-certainty evidence).Four studies examined health promotion activities to encourage people to attend for screening, including mass media strategies and more locally organized activities. There was some increase, but this could have been related to temporal trends, with no corresponding increase in case notifications, and no evidence of an effect on long-term tuberculosis prevalence. Two studies examined the effects of two to six nurse practitioner educational sessions in tuberculosis diagnosis, with no clear effect on tuberculosis cases detected. One trial compared mobile clinics every five days with house-to-house screening every six months, and showed an increase in tuberculosis cases.There was also insufficient evidence to determine if sustained improvements in case detection impact on long-term tuberculosis prevalence; this was evaluated in one study, which indicated little or no effect after four years of either contact tracing, extensive health promotion activities, or both (RR 1.31, 95% CI 0.75 to 2.30; 1 study, 405,788 participants in 12 clusters, very low-certainty evidence).

AUTHORS' CONCLUSIONS

The available evidence demonstrates that when used in appropriate settings, active case-finding approaches may result in increase in tuberculosis case detection in the short term. The effect of active case finding on treatment outcome needs to be further evaluated in sufficiently powered studies.

Standardized radiographic interpretation of thoracic tuberculosis in children

There is a lack of standardized approach and terminology to classify the diverse spectrum of manifestations in tuberculosis. It is important to recognize the different clinical and radiographic patterns to guide treatment. As a result of changing epidemiology, there is considerable overlap in the radiologic presentations of primary tuberculosis and post-primary tuberculosis. In this article we promote a standardized approach in clinical and radiographic classification for children suspected of having or diagnosed with childhood tuberculosis. We propose standardized terms to diminish confusion and miscommunication, which can affect management. In addition, we present pitfalls and limitations of imaging.

Screening strategies for active tuberculosis: focus on cost-effectiveness

In recent years, there has been renewed interest in screening for active tuberculosis (TB), also called active case-finding (ACF), as a possible means to achieve control of the global TB epidemic. ACF aims to increase the detection of TB, in order to diagnose and treat patients with TB earlier than if they had been diagnosed and treated only at the time when they sought health care because of symptoms. This will reduce or avoid secondary transmission of TB to other people, with the long-term goal of reducing the incidence of TB. Here, the history of screening for active TB, current screening practices, and the role of TB-diagnostic tools are summarized and the literature on cost-effectiveness of screening for active TB reviewed. Cost-effectiveness analyses indicate that community-wide ACF can be cost-effective in settings with a high incidence of TB. ACF among close TB contacts is cost-effective in settings with a low as well as a high incidence of TB. The evidence for cost-effectiveness of screening among HIV-infected persons is not as strong as for TB contacts, but the reviewed studies suggest that the intervention can be cost-effective depending on the background prevalence of TB and test volume. None of the cost-effectiveness analyses were informed by data from randomized controlled trials. As the results of randomized controlled trials evaluating different ACF strategies will become available in future, we will hopefully gain a better understanding of the role that ACF can play in achieving global TB control.

Time to symptom resolution in young children treated for pulmonary tuberculosis

BACKGROUND

Response to treatment may be useful for diagnostic confirmation of childhood tuberculosis (TB). We aimed to evaluate time to symptom resolution in children treated for pulmonary TB.

METHODS

We compared pulmonary TB cases and noncases, classified by a published diagnostic algorithm, in South African children younger than 2. TB treatment was prescribed independently on clinical grounds. We analyzed independent determinants of baseline symptom resolution by Cox regression.

RESULTS

One hundred and ninety-one symptomatic children, median age 12 months, were prescribed for TB treatment. Chest radiograph features of TB were associated with longer time to resolution of cough (adjusted hazard ratio, AHR 0.31), wheeze (AHR 0.26) and failure to thrive (AHR 0.41), (all P < 0.05). However, median duration of baseline cough (63 vs. 70 days, P = 0.98), wheeze (62 vs. 68 days, P = 0.87) and failure to thrive (76 vs. 66 days, P = 0.59) did not differ in TB cases (n = 48) versus noncases (n = 46).

CONCLUSIONS

Baseline symptoms take more than 60 days to resolve in the majority of young children after starting TB treatment. Furthermore, since time to resolution does not differentiate TB cases from noncases; clinical response to treatment is not an appropriate diagnostic criterion for pediatric trials of TB diagnostics, drugs and vaccines.

A prospective evaluation of the symptom-based screening approach to the management of children who are contacts of tuberculosis cases

BACKGROUND

Child tuberculosis contact screening and management can enhance case finding and prevent tuberculosis disease. It is universally recommended but rarely implemented in tuberculosis-endemic settings. The World Health Organization (WHO)-recommended symptom-based screening approach could improve implementation but has not been prospectively evaluated.

METHODS

We conducted a cohort study of children who were close contacts of pulmonary tuberculosis patients in Indonesia from August 2010 to December 2012. We performed clinical assessment, tuberculin skin test, and chest radiography in all eligible children irrespective of symptoms at baseline. Mycobacterial culture and Xpert MTB/RIF assay were performed on sputum from children with persistent symptoms of suspected tuberculosis. Children were managed according to WHO guidelines and were prospectively followed for 12 months.

RESULTS

A total of 269 child contacts of 140 index cases were evaluated. At baseline, 21 (8%) children had tuberculosis diagnosed clinically; an additional 102 (38%) had evidence of infection without disease. Of children with any tuberculosis-related symptoms at baseline, 21% had tuberculosis diagnosed compared with none of the asymptomatic children (P < .001). After 12 months of follow-up, none of the 99 eligible young child contacts (<5 years) who received isoniazid preventive therapy (IPT) had developed disease compared with 4 of 149 (2.6%) asymptomatic older children who did not receive IPT.

CONCLUSIONS

Symptom-based screening is an effective and simple approach to child tuberculosis contact management that can be implemented at the primary healthcare level.

Safety and efficacy of MVA85A, a new tuberculosis vaccine, in infants previously vaccinated with BCG: a randomised, placebo-controlled phase 2b trial

BACKGROUND

BCG vaccination provides incomplete protection against tuberculosis in infants. A new vaccine, modified Vaccinia Ankara virus expressing antigen 85A (MVA85A), was designed to enhance the protective efficacy of BCG. We aimed to assess safety, immunogenicity, and efficacy of MVA85A against tuberculosis and Mycobacterium tuberculosis infection in infants.

METHODS

In our double-blind, randomised, placebo-controlled phase 2b trial, we enrolled healthy infants (aged 4–6 months) without HIV infection who had previously received BCG vaccination. We randomly allocated infants (1:1), according to an independently generated sequence with block sizes of four, to receive one intradermal dose of MVA85A or an equal volume of Candida skin test antigen as placebo at a clinical facility in a rural region near Cape Town, South Africa. We actively followed up infants every 3 months for up to 37 months. The primary study outcome was safety (incidence of adverse and serious adverse events) in all vaccinated participants, but we also assessed efficacy in a protocol-defined group of participants who received at least one dose of allocated vaccine. The primary efficacy endpoint was incident tuberculosis incorporating microbiological, radiological, and clinical criteria, and the secondary efficacy endpoint was M tuberculosis infection according to QuantiFERON TB Gold In-tube conversion (Cellestis, Australia). This trial was registered with the South African National Clinical Trials Register (DOH-27-0109-2654) and with ClinicalTrials.gov on July 31, 2009, number NCT00953927.

FINDINGS

Between July 15, 2009, and May 4, 2011, we enrolled 2797 infants (1399 allocated MVA85A and 1398 allocated placebo). Median follow-up in the per-protocol population was 24·6 months (IQR 19·2–28·1), and did not differ between groups. More infants who received MVA85A than controls had at least one local adverse event (1251 [89%] of 1399 MVA85A recipients and 628 [45%] of 1396 controls who received the allocated intervention) but the numbers of infants with systemic adverse events (1120 [80%] and 1059 [76%]) or serious adverse events (257 [18%] and 258 (18%) did not differ between groups. None of the 648 serious adverse events in these 515 infants was related to MVA85A. 32 (2%) of 1399 MVA85A recipients met the primary efficacy endpoint (tuberculosis incidence of 1·15 per 100 person-years [95% CI 0·79 to 1·62]; with conversion in 178 [13%] of 1398 infants [95% CI 11·0 to 14·6]) as did 39 (3%) of 1395 controls (1·39 per 100 person-years [1·00 to 1·91]; with conversion in 171 [12%] of 1394 infants [10·6 to 14·1]). Efficacy against tuberculosis was 17·3% (95% CI −31·9 to 48·2) and against M tuberculosis infection was −3·8% (–28·1 to 15·9).

INTERPRETATION

MVA85A was well tolerated and induced modest cell-mediated immune responses. Reasons for the absence of MVA85A efficacy against tuberculosis or M tuberculosis infection in infants need exploration.

FUNDING

Aeras, Wellcome Trust, and Oxford-Emergent Tuberculosis Consortium (OETC).

Lessons learnt from the first efficacy trial of a new infant tuberculosis vaccine since BCG

BACKGROUND

New tuberculosis (TB) vaccines are being developed to combat the global epidemic. A phase IIb trial of a candidate vaccine, MVA85A, was conducted in a high burden setting in South Africa to evaluate proof-of-concept efficacy for prevention of TB in infants.

OBJECTIVE

To describe the study design and implementation lessons from an infant TB vaccine efficacy trial.

METHODS

This was a randomised, controlled, double-blind clinical trial comparing the safety and efficacy of MVA85A to Candin control administered to 4-6-month-old, BCG-vaccinated, HIV-negative infants at a rural site in South Africa. Infants were followed up for 15-39 months for incident TB disease based on pre-specified endpoints.

RESULTS

2797 infants were enrolled over 22 months. Factors adversely affecting recruitment and the solutions that were implemented are discussed. Slow case accrual led to six months extension of trial follow up.

CONCLUSION

The clinical, regulatory and research environment for modern efficacy trials of new TB vaccines are substantially different to that when BCG vaccine was first evaluated in infants. Future infant TB vaccine trials will need to allocate sufficient resources and optimise operational efficiency. A stringent TB case definition is necessary to maximize specificity, and TB case accrual must be monitored closely.

Cross-protection among Rickettsia species and subspecies in a guinea pig model of cutaneous infection

Pathogenic rickettsiae of the spotted fever group (SFG) induce skin lesions called "eschars" at the sites of arthropod bites. We recently described a guinea pig model based on eschar formation to predict the eventual pathogenicity of new Rickettsia species, and in this study, we used the model to study cross-protection among SFG Rickettsia species and subspecies. We showed that the intradermal inoculation of guinea pigs with Rickettsia conorii subsp. conorii significantly reduced, but not completely prevented, the number of eschars after sub-challenges with the same pathogen (P=0.0004). The same effect was also observed for other subspecies of the R. conorii complex. Additionally, the bacterial load in the eschars was significantly lower in immunized animals than in naïve animals. No protection was observed when sub-challenges were performed with other Rickettsia species, such as R. africae, R. sibirica subsp. mongolitimonae, R. aeschlimannii and R. massiliae. Our data suggest that patients may experience several episodes of infection with related or with the same species of Rickettsia. Moreover, the absence of cross-protection between Rickettsia species may explain the co-existence of two or more tick-borne rickettsioses in the same geographic areas.